Supernumerary kidney

What it is

A rare non-syndromic renal/urinary tract malformation characterized by the presence of more than two kidneys (up to five), each of which mostly has its own collecting system, vascular supply, and distinct encapsulated parenchyma. The additional kidney(s), smaller than native ones, mostly occurs ipsilateral and caudal to the left kidney and may be fused to the native kidneys. Patients are usually asymptomatic but they may present with symptoms such as pain, a palpable abdominal mass, fever and sometimes with urinary symptoms (such as urinary incontinence) when supernumerary kidneys occur with an ectopic ureter. Additional congenital abnormalities including horseshoe kidney malformation, ventricular septal defect, and cloacal abnormalities (such as urethral atresia, vaginal atresia, ectopic ureter implantation, imperforate anus, and duplication of urethra) may also be present in some patients.

Key facts

Prevalence

<1 / 1 000 000

Age of onset

Neonatal

Inheritance

Unknown

Classified as

Morphological anomaly

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

ICD-10 codes

Cross-references